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/* Instantiate a public key crypto key from an X.509 Certificate
*
* Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#define pr_fmt(fmt) "X.509: "fmt
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/mpi.h>
#include <linux/asn1_decoder.h>
#include <keys/asymmetric-subtype.h>
#include <keys/asymmetric-parser.h>
#include <keys/system_keyring.h>
#include <crypto/hash.h>
#include <crypto/public_key.h>
#include "asymmetric_keys.h"
#include "x509_parser.h"
static bool use_builtin_keys;
static struct asymmetric_key_id *ca_keyid;
#ifndef MODULE
static struct {
struct asymmetric_key_id id;
unsigned char data[10];
} cakey;
static int __init ca_keys_setup(char *str)
{
if (!str) /* default system keyring */
return 1;
if (strncmp(str, "id:", 3) == 0) {
struct asymmetric_key_id *p = &cakey.id;
size_t hexlen = (strlen(str) - 3) / 2;
int ret;
if (hexlen == 0 || hexlen > sizeof(cakey.data)) {
pr_err("Missing or invalid ca_keys id\n");
return 1;
}
ret = __asymmetric_key_hex_to_key_id(str + 3, p, hexlen);
if (ret < 0)
pr_err("Unparsable ca_keys id hex string\n");
else
ca_keyid = p; /* owner key 'id:xxxxxx' */
} else if (strcmp(str, "builtin") == 0) {
use_builtin_keys = true;
}
return 1;
}
__setup("ca_keys=", ca_keys_setup);
#endif
/*
* Check the new certificate against the ones in the trust keyring. If one of
* those is the signing key and validates the new certificate, then mark the
* new certificate as being trusted.
*
* Return 0 if the new certificate was successfully validated, 1 if we couldn't
* find a matching parent certificate in the trusted list and an error if there
* is a matching certificate but the signature check fails.
*/
int x509_validate_trust(struct x509_certificate *cert,
struct key *trust_keyring)
{
struct public_key_signature *sig = cert->sig;
struct key *key;
int ret = 1;
if (!sig->auth_ids[0] && !sig->auth_ids[1])
return 1;
if (!trust_keyring)
return -EOPNOTSUPP;
if (ca_keyid && !asymmetric_key_id_partial(sig->auth_ids[1], ca_keyid))
return -EPERM;
if (cert->unsupported_sig)
return -ENOPKG;
key = find_asymmetric_key(trust_keyring,
sig->auth_ids[0], sig->auth_ids[1],
false);
if (IS_ERR(key))
return PTR_ERR(key);
if (!use_builtin_keys ||
test_bit(KEY_FLAG_BUILTIN, &key->flags)) {
ret = verify_signature(key, cert->sig);
if (ret == -ENOPKG)
cert->unsupported_sig = true;
}
key_put(key);
return ret;
}
EXPORT_SYMBOL_GPL(x509_validate_trust);
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